Side-channel attack is one of the powerful attack techniques against encryption algorithms. The side-channel attack is gradually becoming a large threat to security products. Among the side-channel attack, power/electromagnetic wave side-channel analysis is an attack method by which secret information (mainly, key information) of encryption algorithm is analyzed by collecting power consumptions or electromagnetic waves generated when driving the encryption algorithm and statistically analyzing them.
In order to avoid such power/electromagnetic wave side-channel analysis attack, various prevention techniques have been suggested. Among them, a masking technique is a typical method of preventing the side-channel analysis attack at an algorithm level. The masking technique makes it difficult to extract secret information through statistical analysis of collected power waveforms or electromagnetic wave data by adding random data to original data to be encrypted or performing a logical operation (e.g., exclusive OR (XOR) operation).
However, in the case of composing a masking F-function, the conventional masking method has a problem that the procedure of converting an arithmetic operation mask value, e.g., a 232 modular addition mask value, into a logical operation mask value, e.g., an XOR mask value has to be repeated many times.